Method and system of maintaining dpf regeneration for improving durability of dpf filter

ABSTRACT

A method of maintaining diesel particulate filter (DPF) regeneration for improving durability of a DPF, may include determining, by a controller, whether a vehicle enters an idle state during the DPF regeneration, controlling, by the controller, a concentration of oxygen introduced into the DPF to be equal to or less than a first reference value when the vehicle enters the idle state, and performing, by the controller, a regeneration process until a soot mass in the DPF may be equal to or less than a target reference value.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application Number 10-2014-0099728 filed Aug. 4, 2014, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and a system of maintaining diesel particulate filter (DPF) regeneration for improving durability of a DPF filter, and more particularly, to a method and a system of maintaining DPF regeneration for improving durability of a DPF filter by maintaining the DPF regeneration until a soot mass in the DPF is equal to or less than a set target reference value even when a vehicle enters an idle state while the vehicle is driven.

2. Description of Related Art

Exhaust gas emitted from an engine is induced into and purified by a catalytic converter which is disposed in the middle of an exhaust pipe and emitted into the air through a tail exhaust pipe after noise is reduced while passing through a muffler.

Meanwhile, the exhaust gas emitted from the engine needs to meet OBD regulations which define a regulation of exhaust gas and several regulations associated with standardization in a diagnosis and after service (A/S) market detecting a failure and a deterioration of exhaust related parts.

Therefore, to meet North America Diesel Tier2 BIN5 regulation or Euro 6 regulation, a diesel vehicle has used an oxidation catalyst, a diesel particulate filter (DPF), a selective catalytic reduction (SCR) catalyst, and the like and a combination and a disposition position of the catalysts are differently determined depending on a design of the vehicle.

In this case, a diesel particulate filter physically captures particulate materials such as soot included in exhaust gas and when the diesel particulate filter captures the particulate materials after a vehicle drives a predetermined distance or at a difference pressure between both ends thereof which is equal to or more than a set reference pressure, the captured materials are combusted and regenerated due to exhaust gas which rises to a high temperature of approximately 500 to 650° C. depending on a post-injection control.

Meanwhile, when the vehicle enters an idle state while the diesel particulate filter regenerates the particulate materials depending on the post-injection control, oxygen concentration is increased and a flux of exhaust gas is reduced to cause abnormal DPF regeneration. In this case, when the diesel particulate filter exceeds an endurance limit temperature and a limit temperature gradient of a filter, melting, cracks, and the like occur in the diesel particulate filter, such that the diesel particulate filter may be damaged.

Generally, the DPF filter may be mainly made of materials such as SiC and cordierite which may be damaged. In this case, the endurance limit temperature of the filter is approximately 1100° C. and the limit temperature gradient is approximately 400° C./cm.

As described above, when the vehicle enters the idle state during the DPF regeneration process, the oxygen concentration is increased and the flux of exhaust gas is reduced to cause the abnormal DPF regeneration, such that the DPF may be damaged.

FIG. 1 is a graph illustrating an operation temperature of the filter and a gradient temperature of the filter when the vehicle enters the idle state during the DPF regeneration process. As illustrated in FIG. 1, the DPF regeneration process is made while the engine is driven at approximately 2000 rpm and the oxygen concentration of a front end of the DPF is controlled to be 15% or less in section “A” in which a general driving state is represented and the vehicle is driven at approximately 700 to 800 rpm and the oxygen concentration of the front end of the DPF is controlled to be 8% or less when the vehicle enters the so-called idle state during drop to idle (section “B”) and then the oxygen concentration of the front end of the DPF is not controlled in a section “C”.

In this case, when the vehicle enters the idle state and the DPF regeneration process exits after a predetermined time lapses, as illustrated, the operation temperature of the filter rises, and thus reaches point “a” which is a highest temperature and the gradient temperature of the filter also reaches point “b” which is a highest temperature.

That is, when the generation process exits in the state in which a large amount of soot is still present in the DPF, the oxygen concentration is increased and when an excessive amount of oxygen is supplied to an ignited filter, the temperature in the filter suddenly rises and thus the gradient temperature of the filter also suddenly rises.

Therefore, the damage possibility of the DPF is increased, and therefore the present invention relates to a method and a system of maintaining DPF regeneration for improving durability of a DPF filter for solving the existing problems.

The related art for solving the existing problems as described above is disclosed. In connection with the related art, a related art entitled “Apparatus And Method For Protection Diesel Particulate Filter” is implemented by determining whether abnormal DPF regeneration occurs when a vehicle enters an idle state during the generation of the diesel particulate filter to prevent the diesel particulate filter from rising to a limit temperature or more but has a limitation that it does not disclose the technical spirit of the present invention which maintains the DPF regeneration for a predetermined time even when the vehicle enters the idle state until a soot mass in the DPF is a predetermined reference value or less.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing a method and a system of maintaining DPF regeneration for improving durability of a DPF filter capable of preventing a damage of the DPF by maintaining the DPF regeneration process until a soot mass in the DPF is equal to or less than a set target reference value even when a vehicle enters an idle state during the DPF regeneration process so as to prevent the damage of the DPF which occurs when the vehicle enters the idle state during the DPF regeneration process.

In an aspect of the present invention, a method of maintaining diesel particulate filter (DPF) regeneration for improving durability of a DPF, may include determining, by a controller, whether a vehicle enters an idle state during the DPF regeneration, controlling, by the controller, a concentration of oxygen introduced into the DPF to be equal to or less than a first reference value when the vehicle enters the idle state, and performing, by the controller, a regeneration process until a soot mass in the DPF is equal to or less than a target reference value.

The method may further include, after the determining whether the vehicle enters the idle state during the DPF generation, comparing, by the controller, the soot mass in the DPF with a preset soot reference value when the vehicle enters the idle state.

The method may further include, in the comparing of the soot mass in the DPF with the preset soot reference value when the vehicle enters the idle state, when the soot mass in the DPF is equal to or more than the preset soot reference value, controlling, by the controller, the concentration of the oxygen introduced into the DPF to be equal to or less than the first reference value, and when the soot mass in the DPF is less than the preset soot reference value, controlling, by the controller, the concentration of the oxygen introduced into the DPF to be equal to or less than a second reference value larger than the first reference value.

The concentration of the oxygen introduced into the DPF is controlled by using a shutoff valve installed in front of an engine.

In another aspect of the present invention, a system of maintaining DPF regeneration for improving durability of a diesel particulate filter (DPF), may include the DPF capturing a soot captured in exhaust gas, and a controller receiving a signal about whether a vehicle is currently in an idle state to maintain the DPF regeneration in the idle state of the vehicle until a soot mass in the DPF reaches a target reference value to prevent the DPF from arriving at a limit temperature and a limit temperature gradient.

The controller receives the signal about whether the vehicle is currently in the idle state and controls a concentration of oxygen introduced into the DPF to be equal to or less than a first reference value to maintain the DPF regeneration until the soot mass in the DPF reaches the target reference value.

The controller receives the signal about whether the vehicle is currently in the idle state and then determines whether the soot mass in the DPF is equal to or more than a preset soot reference value.

The controller controls the concentration of the oxygen introduced into the DPF to be equal to or less than the first reference value when the soot mass in the DPF is equal to or more than the preset soot reference value, and when the soot mass in the DPF is less than the preset soot reference value, controlling, by the controller, the concentration of the oxygen introduced into the DPF to be equal to or less than a second reference value larger than the first reference value to maintain the DPF regeneration until the soot mass in the DPF reaches the target reference value.

The controller transfers a signal to a shutoff valve installed in front of an engine to control a concentration of oxygen introduced into the DPF.

It is understood that the term “vehicle” or “vehicular” or other similar terms as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuel derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example, both gasoline-powered and electric-powered vehicles.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph illustrating a variation of an operation temperature and a gradient temperature of a DPF which occurs while exiting a DPF regeneration process when a vehicle enters an idle state while the vehicle is driven, according to the related art.

FIG. 2 and FIG. 3 are flow charts of a method of maintaining DPF regeneration for improving durability of a DPF filter according to an exemplary embodiment of the present invention.

FIG. 4 is a flow chart illustrating a detailed control for each process of the method of maintaining DPF regeneration for improving durability of a DPF filter according to an exemplary embodiment of the present invention.

FIG. 5 is a graph confirming that durability of DPF is improved by a control logic according to an exemplary embodiment of the present invention.

FIG. 6 is a graph illustrating a concentration of oxygen introduced into the DPF and a soot mass remaining within the DPF depending on a control process according to an exemplary embodiment of the present invention.

FIG. 7 is a schematic diagram of a system of maintaining DPF regeneration for improving durability of a DPF filter according to an exemplary embodiment of the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

FIG. 2 is an overall flow chart of a method of maintaining DPF regeneration for improving durability of a DPF filter according to various embodiments of the present invention. As illustrated in FIG. 2, the method of maintaining DPF regeneration for improving durability of a DPF filter according to various embodiments of the present invention largely includes determining whether a vehicle enters an idle state (S100), controlling a concentration of oxygen introduced into the DPF to be equal to or less than a set first reference value (S200), and performing a DPF regeneration process until a soot mass in the DPF is equal to or less than a set target reference value (S300).

First, the determining whether the vehicle enters the idle state during the regeneration process of the DPF filter is performed (S100) and it may be detected whether the vehicle enters the idle state based on various information such as an acceleration pedal signal and a gear ratio.

Meanwhile, it is confirmed that the vehicle enters the idle state during the DPF regeneration process by using several signal of the vehicle as described above, the controlling of the concentration of oxygen introduced into the DPF to be equal to or less than the set first reference value is performed (S200).

That is, the oxygen concentration is controlled to be equal to or less than the set first reference value to prevent the DPF filter from being exposed to a high temperature for improving the durability of the DPF, in which the oxygen concentration which is the first reference value may be controlled to 8% or so.

Meanwhile, the regeneration process is performed until an amount of soot in the DPF is equal to or less than the set target reference value while the concentration of oxygen introduced into the DPF is controlled to be equal to or less than the first reference value as described above.

That is, according to the related art, the DPF regeneration process exits after the predetermined time lapses when the vehicle enters the idle state during the DPF regeneration process. In this case, the regeneration process is suspended while a large amount of soot still remains in the DPF, and then, the oxygen concentration is increased, such that the temperature of the DPF filter may rise while the soot burning in the DPF is excessively burned due to the excessively supplied oxygen. To prevent the above problem, various embodiments of the present invention have a characteristic in that the DPF regeneration process is maintained until the soot mass in the DPF falls to the set target reference value or less even though the vehicle enters the idle state during the DPF regeneration process.

Meanwhile, the target reference value may be set to be 2% but a volume of the DPF is diverse. Generally, if it is assumed that the target reference value is 100% when the soot mass of 8 g per a volume 1 L of the DPF is present, the regeneration process is performed until the target reference value reaches 2% based on the amount.

Further, as well known, the method for measuring a soot mass in a DPF measures a soot mass based on a pressure difference using pressure sensors installed at front and rear ends of the DPF.

By the foregoing process, while the concentration of oxygen introduced into the DPF is controlled even though the vehicle enters the idle state during the regeneration process, the regeneration process is performed until the soot mass in the DPF is equal to or less than the set target reference value to prevent the DPF from arriving at a maximum limit temperature and a limit temperature gradient of the DPF filter, such that it is possible to previously prevent the DPF from being damaged.

Meanwhile, as illustrated in FIG. 3, the method of maintaining DPF regeneration for improving durability of a DPF filter according to various embodiments of the present invention further includes comparing the soot mass in the DPF with a preset soot reference value when the vehicle enters the idle state (S110) after determining whether the vehicle enters the idle state during the regeneration of the DPF (S100). That is, when the soot mass in the DPF is equal to or more than 30% which is the soot reference value, the soot mass in the DPF is much and thus a lot of the soot are excessively burned to excessively rise the temperature of the DPF when the concentration of oxygen introduced into the DPF is excessively higher and thus the concentration of oxygen introduced into the DPF is controlled to be equal to or less than the set first reference value.

In this case, in the comparing of the soot mass in the DPF with the preset soot reference value when the vehicle enters the idle state (S110), when the soot mass in the DPF is equal to or more than the preset soot reference value, the method of maintaining DPF regeneration for improving durability of a DPF filter according to various embodiments of the present invention further includes controlling the concentration of oxygen introduced into the DPF to be equal to or less than a first reference value, and when the soot mass in the DPF is less than the preset soot reference value, controlling, by the controller, the concentration of the oxygen introduced into the DPF to be equal to or less than a second reference value larger than the first reference value in which the second reference value may be set to be 15%.

That is, in case which the soot mass in the DPF is less than 30%, the soot mass in the DPF to be burned oxygen introduced into the DPF is relatively smaller, even when the concentration of oxygen introduced into the DPF is controlled to be 15%, not to be 8%. Thus, the regeneration of the DPF can be swiftly completed while damage of the DPF is prevented because temperature rise of the DPF is relatively smaller compared with that in case which the soot mass in the DPF is more than 30%.

Meanwhile, FIG. 4 is a flow chart illustrating a detailed control for each process of the method of maintaining DPF regeneration for improving durability of a DPF filter according to various embodiments of the present invention.

The detailed control method is described in advance, and therefore is omitted herein. However, the regeneration process is performed until the soot mass in the DPF is equal to or less than the set target reference value and then the regeneration process ends and after it is confirmed whether the engine of the vehicle starts, if it is determined that the engine does not start, the control logic ends and if it is determined that the engine starts, it is again determined whether the soot mass in the DPF is 100% and then the control logic as described above is again performed.

FIG. 5 is a graph illustrating an experiment result that the durability of the DPF is improved by maintaining the regeneration process by the foregoing control process until the soot mass in the DPF is equal to or less than the target reference value even when the vehicle enters the idle state during the regeneration process.

As illustrated, the regeneration process is performed until the soot mass in the DPF is equal to or less than the target reference value when the vehicle enters the idle state during the regeneration process and thus an operation temperature X of the DPF and a gradient temperature Y in the filter are formed to be smaller than a limit value as compared with the related art, thereby confirming that the durability of the DPF is improved.

For reference, region “A” is a region in which the concentration of oxygen introduced into the DPF is controlled to be equal to or less than 15%, region “B” is a region in which the concentration of oxygen intruded into the DPF is controlled to be equal to or less than 8%, region “C” is a region in which the concentration of oxygen again introduced into the DPF is controlled to be equal to or less than 15%, and region “D” is a region in which the concentration of oxygen introduced into the DPF is no more controlled.

Further, FIG. 6 is a graph illustrating a change in a variation of the soot mass in the DPF by controlling an engine speed and the concentration of oxygen introduced into the DPF according to various embodiments of the present invention.

As illustrated, the concentration of oxygen introduced into the DPF according to various embodiments of the present invention is controlled when the vehicle enters the idle state while the regeneration process is performed while the vehicle is driven and the regeneration process is performed until the soot mass in the DPF is equal to or less than the set target reference value, thereby improving the durability of the DPF.

Meanwhile, the concentration of oxygen introduced into the DPF is controlled by using a shutoff valve installed in front of the engine.

FIG. 7 is an overall configuration diagram of a system of maintaining DPF regeneration for improving durability of a DPF filter according to various embodiments of the present invention. As illustrated, the system includes the DPF capturing the soot captured in exhaust gas and a controller 100 which receives a signal about whether the vehicle is currently in the idle state to maintain the regeneration in the idle state of the vehicle until the soot mass in the DPF reaches the set target reference value so as to prevent the DPF from arriving at the limit temperature and the limit temperature gradient.

The controller 100 receives the signal about whether the vehicle is currently in the idle state and controls the concentration of oxygen introduced into the DPF to be equal to or less than the first reference value to maintain the regeneration until the soot mass in the DPF reaches the set target reference value.

Further, the controller 100 further includes receiving the signal about whether the vehicle is currently in the idle state and then controlling the concentration of the oxygen introduced into the DPF to be equal to or less than the first reference value when the soot mass in the DPF is equal to or more than the preset soot reference value, and when the soot mass in the DPF is less than the preset soot reference value, controlling, by the controller, the concentration of the oxygen introduced into the DPF to be equal to or less than a second reference value larger than the first reference value until the soot mass in the DPF reaches the set target reference value.

The detailed control method thereof has been described above, and a description thereof will be omitted herein.

According to the method and system of maintaining DPF regeneration for improving durability of a DPF filter according to various embodiments of the present invention by the configuration and control as described above, it is possible to improve the durability of the DPF by performing the DPF regeneration process until the soot mass in the DPF falls to the target reference value or less even when the vehicle enters the idle state during the DPF regeneration process.

According to the method and system of maintaining DPF regeneration for improving durability of a DPF filter according to various embodiments of the present invention configured as described above, it is possible to improve the durability of the DPF by controlling the amount of oxygen introduced into the DPF for the temperature of the DPF to be below the endurance limit temperature and the limit temperature gradient of the DPF filter and performing the DPF regeneration process until the soot mass in the DPF is equal to or less than the target reference value.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

1. A method of maintaining diesel particulate filter (DPF) regeneration for improving durability of a DPF, comprising: determining, by a controller, whether a vehicle enters an idle state during the DPF regeneration; controlling, by the controller, a concentration of oxygen introduced into the DPF to be equal to or less than a first reference value when the vehicle enters the idle state; and performing, by the controller, a regeneration process until a soot mass in the DPF is equal to or less than a target reference value.
 2. The method of claim 1, further comprising: after the determining whether the vehicle enters the idle state during the DPF generation, comparing, by the controller, the soot mass in the DPF with a preset soot reference value when the vehicle enters the idle state.
 3. The method of claim 2, further comprising: in the comparing of the soot mass in the DPF with the preset soot reference value when the vehicle enters the idle state, when the soot mass in the DPF is equal to or more than the preset soot reference value, controlling, by the controller, the concentration of the oxygen introduced into the DPF to be equal to or less than the first reference value, and when the soot mass in the DPF is less than the preset soot reference value, controlling, by the controller, the concentration of the oxygen introduced into the DPF to be equal to or less than a second reference value larger than the first reference value.
 4. The method of claim 3, wherein the concentration of the oxygen introduced into the DPF is controlled by using a shutoff valve installed in front of an engine.
 5. A system of maintaining DPF regeneration for improving durability of a diesel particulate filter (DPF), comprising: the DPF capturing a soot captured in exhaust gas; and a controller receiving a signal about whether a vehicle is currently in an idle state to maintain the DPF regeneration in the idle state of the vehicle until a soot mass in the DPF reaches a target reference value to prevent the DPF from arriving at a limit temperature and a limit temperature gradient.
 6. The system of claim 5, wherein the controller receives the signal about whether the vehicle is currently in the idle state and controls a concentration of oxygen introduced into the DPF to be equal to or less than a first reference value to maintain the DPF regeneration until the soot mass in the DPF reaches the target reference value.
 7. The system of claim 6, wherein the controller receives the signal about whether the vehicle is currently in the idle state and then determines whether the soot mass in the DPF is equal to or more than a preset soot reference value.
 8. The system of claim 7, wherein the controller controls the concentration of the oxygen introduced into the DPF to be equal to or less than the first reference value when the soot mass in the DPF is equal to or more than the preset soot reference value, and when the soot mass in the DPF is less than the preset soot reference value, controlling, by the controller, the concentration of the oxygen introduced into the DPF to be equal to or less than a second reference value larger than the first reference value to maintain the DPF regeneration until the soot mass in the DPF reaches the target reference value.
 9. The system of claim 5, wherein the controller transfers a signal to a shutoff valve installed in front of an engine to control a concentration of oxygen introduced into the DPF. 